Diamond treatments

If a diamond is treated before it is sold, this means that something has been done to improve the appearance of the stone.

All jewellers and online retailers should disclose whether a diamond has been treated or not. You should always bear in mind that treated diamonds are not as valuable as untreated diamonds, and if a retailer tries to convince you otherwise then walk away.

To ensure you are not buying a treated diamond, only by a stone with an accompanying independent lab report. It’s becoming harder and harder to detect certain treatments and independent lab documents are becoming more necessary.

Diamonds are treated to improve either their color or clarity.

Methods for changing color include:

• foilbacking
• irradiation
• annealing
• coating, tinting and painting
• high pressure and high temperature (HPHT)
• high temperature heat treatment

Methods for improving clarity include:

• laser drilling
• fracture filling

Select the appropriate menu item in this section to read more about each treatment technique.